Cellular isolation techniques are an essential component in studying specific populations, allowing for growth, genomic, and proteomic investigations. The detachment of cells adhered to any surface requires the application of a force that is greater in magnitude to that of adhesion. Fluid shear forces have been shown to be a simple method for cell detachment. Although this is a local and simple method of cell release, excessive exposure to fluid shear results in cell damage and reduction in viability. An alternative approach is to cleave the protein ligand that is bound to the capture surface using enzymes, such as trypsin. However, enzymatic exposure can cause morphological changes due to a disruption of the cell membrane and glycocalyx, leading to losses in cellular activity. Furthermore, enzymatic digestion has been shown to directly affect both the behavior and chemical makeup of the cells themselves.
Current techniques, such as fluorescent activated cell sorting (FACS) and magnetic activated cell sorting (MACS), in cell isolation have disadvantages in fields such as tissue engineering. Conventional method of cell isolation, FACS, presents limited throughput which can be detrimental to the cell viability. The FACs method is limited in its ability to multiplex, which leads to sample processing time to decrease substantially.
These limitations illustrate the need to establish a general technique to capture and release biological materials, such as cells, in micro-scale devices without extensive physical or chemical perturbations to the cell environment. There remains a need for surfaces and gels that have high specificity for particular cells and that allow the release of captured cells without altering the behavior and makeup of the cells.